Air Injection System Honda Civic III

DESCRIPTION

All carbureted models (except 1300/1500 HF) are equipped with a Pulse Air System (also called Secondary Air Supply System). This system makes use of vacuum pulses in exhaust manifold to draw air from air cleaner to exhaust manifold.

OPERATION

When vehicle exceeds set speed of speed sensor and manifold vacuum is above set vacuum of control switch, the control switch solenoid valve and control switch are open. The control unit energizes the air suction control solenoid valve to apply manifold vacuum to the air suction cut-off diaphragm valve, which opens the secondary air passage.

When vacuum, induced by pulsation in exhaust manifold, makes air suction reed valve open, fresh air enters exhaust manifold. The control switch bellows adjust their operation in response to atmospheric pressure. Air chambers act as silencers to reduce exhaust noise.

1500 Pulse Air System. Scheme 15

CONTROL UNIT CONNECTOR

1. Check for voltage at control unit connector (Blue wire) with ignition on. There should be voltage. If there is no voltage, check Blue wire between ignition coil and control unit.
2. Check for voltage at Black/Yellow wire with ignition on. There should be voltage. If there is no voltage, check wiring. Check Black wire on 1300/1500 HF models) for continuity between control unit and ground. There should be continuity.

INTAKE AIR TEMPERATURE SENSOR

Disconnect air intake temperature sensor connector. Check for continuity when air temperature is below 40°F (4.5°C). Check for no continuity when air temperature is above 73°F (23°C). Replace sensor if sensor does not test as specified.

1500 Except HF

1. Disconnect vacuum hose No. 15 to vacuum switch C and connect a hand vacuum pump to the hose. Apply vacuum to switch. Check for voltage at Black/Red wire of vacuum switch C.
2. Voltage should be available when a vacuum less than 6 in. Hg (all except California with manual transmission) and 3 in. Hg (California with manual transmission) is applied. If there is no voltage, replace the vacuum switch C and retest.

Cold Engine

1. Ensure engine coolant is below 122°F (50°C). Disconnect vacuum hose No. 27. Attach vacuum gauge to vacuum hose at tubing manifold. Check for vacuum at idle speed. There should be vacuum. If vacuum is present, proceed to HOT ENGINE test.
2. If no vacuum, disconnect other hose and check for vacuum at hose. If there is vacuum, replace thermovalve C and retest. If no vacuum at hose, check auxiliary intake vacuum hose for leaks or blockage.

Scheme 16

1. Warm engine to operating temperature. Check operation of thermovalve C. Attach vacuum gauge to vacuum hose No. 27 at tubing manifold. There should be no vacuum at idle. If there is no vacuum, check air suction valve. If there is vacuum, replace thermovalve C and retest.
2. To check air suction valve, remove air cleaner cover and filter. Start engine and run at idle speed. Check for bubbling noise from air suction port. (Scheme 16) If bubbling noise is heard, proceed to step 3). (Scheme 16): Air Suction Port Location
3. If bubbling noise is not heard, disconnect hose No. 5 from air suction cut-off diaphragm and check for vacuum. If vacuum is present, replace air suction cut-off diaphragm and retest. If no vacuum is present, reconnect vacuum hose No. 5.
4. Disconnect hose No. 32 from control box at vacuum hose manifold and check for vacuum at vacuum hose manifold. There should be vacuum. If there is no vacuum, check vacuum hose No. 32 for blockage or leakage. If okay, replace air bleed valve B and retest.
5. If there is vacuum, check for voltage at air suction control valve in box No. 1 (Blue/Green wire on man. trans. and Green/Red wire on auto. trans.). If there is no voltage, check intake air temperature sensor and vacuum switch C.
6. Check for voltage at control unit Black/Yellow wire with ignition on. There should be voltage. If no voltage, check wiring. Check Brown/Black wire for continuity between control unit and ground. It should have continuity.
7. If voltage is present, replace air suction control valve and retest. Raise engine speed above 3500 RPM. If a bubbling noise is not heard, system is okay. If bubbling noise is heard, check for voltage at air suction control solenoid valve (Green/Red wire on auto. trans. and Blue/Green wire on man. trans.) in box No. 1.
8. If there is voltage, check intake air temperature sensor and vacuum switch C. Check for voltage at control unit Black/Yellow wire with ignition on. There should be voltage. If no voltage, check wiring. Check Brown/Black wire for continuity between control unit and ground. It should have continuity.
9. If there is no voltage, replace the air suction control solenoid valve and retest. Heat air bleed valve to 140°F (60°C). Ensure bubbling noise stops. If not, replace air bleed valve B.